Dual pump



May 2, 1944 W. E. CUMMINS 2,347,887

INVENT OR.-

WE EUMMINE May 2, 1944. w. E. cuMMlNs DUAL PUMP Filed Jan. 18, 1945 2 Sheets-Sheet 2 Io n H 3 u o m w wwn un.. .n n f .fn

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INVENTOR. W. EEUMMINE TTM/V57 Patented May 2, 1944 l UNITED sTATEs PATENT OFFICE 2,347,887 DUAL PUMP Walter E. Cummins, Los Angeles, Calif. `Application January 18, 1943, Serial No. 472,713

(Cl. S-172) Claims.

This invention relates to dual pumps.

'I'he general object of the invention is to provide an improved pump for elevating oil, water or other fluids. 1

A more specific object of the invention is to provide a novel pump wherein the fluid is elevated, or moved, or discharged by the successive action of a pair of pistons working in a pump barrel and wherein the use of ball valves, ilap valves, butterfly valves, etc. is avoided so that the cutting action of the abrasives in the liquid being moved does not seriously impair the operation of the pump.

Another-object of the invention is to provide a pump including a discharge pipe, a Working barrel and a novel valve member which reciprocates in a portion of the .barrel and which is provided with pistons which operate in another portion of the barrel to produce the pumping action.

Other objects and the advantages of my invention will be apparent from the following description taken in connection with the accompanying drawings wherein:

Fig. 1 is a central sectional viewwith parts in elevation showing my improved pump installed inawell;

Fig. 2 is an enlarged, fragmentary central, sectional view showing the working barrel;

Fig. 3 is a side elevation of the valve member;

Fig. 4 is an end view of the valve member;

Fig. 5 is a fragmentary sectional view showing the upper piston and associated parts;

Fig. 6 is a section taken on line 6-6, Fig. 5;

Fig. '7 is an extended side elevation showing a modified valve member before nal assembly;

Fig. 8 is a view similar to Fig. 2 on a reduced scale showing the modliied valve `member in position in the working barrel, and

Fig. 9 is a view similar to Fig. 2 showing a `further modification.

Referring to the drawings by reference characters `I have shown my invention as embodied in a dual pump which is indicated generally at I0. As shown the pump is mounted in a well casing I I which may be suspended in a Water, oil or other well. which is suitably supported and which includes an outlet I3.

The lower end of 'the discharge pipe I2 is threaded, as at Il, and engages threads I5 on the lower end of a cylinder I6. The/ cylinder I6 is threaded as at Il and supports a depending pump barrel I8. The upper end I9 of the cylinder is threaded as at 20 to engage similar 55 the piston 34 and in doing S0 has passed through The pump includes a discharge pipe I2 threads on the lower end of an upper pump barrel 2I. The cylinder I6 is spaced as at 22 from the discharge pipe I2 so that an annular passageway is provided.

In the pump barrel portions I8 and 2l and also in the cylinder I6 I arrange a sucker rod 23. This sucker rod has a lower piston 24 thereon arranged in the portion lI8 of the Working barrel and a piston 25 arranged in the portion 2I of the working barrel.

The cylinder I6 is provided with an upper set of apertures 26 and a lower set of apertures 2l. These apertures 26 and 2l are circumferentially aligned with similar apertures 28 and 29 in the discharge pipe I2. Tubular members 30 are secured in the apertures 26 and 28 and other tubular members 3| are secured in the apertures 2l and 29. The tubular members 30 and 3| afford communication between the interior of the cylinder IB and the exterior of the discharge pipe I2 but do not afford communication to the space 22 between the discharge pipe I2 and the cylinder I6.

The cylinder I6 is also provided with an upper set of apertures 32 and a lower set of apertures 33. The apertures 32 and 33 are circumferentially arranged and afford communication between the interior of the cylinder I6 and the space 22 between the cylinder I 6 and the discharge member I2.

Within the cylinder I6 I arrange a valve member 34 which has a central partition 35 and upper and lower packing receiving chambers 36 and3l with the packing held in place by packing nuts 38 and 38. The packing nuts 38 and 39 as well as the partition 35 have apertures which slidably receive the sucker rod 23.

The length of the valve member 34 is such that when the valve member is in the lowered position, as shown in Fig. l2, the apertures 32 are opened, while when the valve member is in the upper position the apertures 33 are opened.

The valve member 34 is provided with an upper circumferential recess 40 and a lower circumferential recess 4I and is also provided with longitudinally extending holes 42 which extend down wardly and intersect the recess 40 and with sim-- ilarly upward extending holes 43 which extend upwardly and intersect the recess 4 I.

The recesses 40 and 4I are spaced apart a distance which is less than the distance between the tubular members `3l! and 3|.

In the operation of my pump, when the sucker rod has moved to the position shown in Fig. 2, liquid has been drawn into the space A above the tubular members 3|, the recess 4| and the longitudinal holes 43 in the valve member. As the sucker rod 23 moves upwardly the liquid in the space A is lifted and this lifts the valve member 34. The recess 4I passes beyond the tubular members 3l and the valve member rises until the apertures 33 are opened.

As the sucker rod continues its upward movement the liquid in the space A passes through the apertures 33 into the space 32 whence it iiows upwardly in the discharge pipe. The upward movement of the valve member 34 has placed the tubular members 30 in communication with the recess 40 so that as the piston 25 rises liquid is drawn into the space B from the holes 42, recess 40 and tubular members 30.

When the sucker rod again starts downwardly the valve member 34 is moved downwardly to the position shown in Fig. 2 and the liquid in the space B is forced into the space 22 whence it passes upwardly through the discharge pipe.

My improved pump does away with the use of ball valves, flap valves and structures of similar. nature which are quickly cut away by sand or other abrasive material in the liquid being pumped.

In order to facilitate assembly of thepump I show in Figs. and 6 details of a guide and holding device. As shown the sucker rod is provided with a portion 53 which isV .shown as square in cross section. The lower end of this portion 50 is rounded and threaded as at 5l to engage a coupling member 52 on the sucker rod 23 just above the piston 25 while the upper end of the portion 50 is threaded at 53 to engage a coupling 54 by means of which it is secured to the sucker rod thereabove. The pump barrel 2l in the locality of the square `portion 50 of the sucker rod includes a coupling 55.

rI'he coupling 55 (see Fig. 6) is provided with a guide and stop member 56 which includes a central body 51 having a rectangular hole 58 therethrough. The body 5l includes arms 59. The body 5l and the arms 59 are engaged by and secured to opposed holding members 60 which are secured in the coupling 55. The hole 69 is square and is slightly larger than the square portion 50 of the sucker rod so that the sucker rod moves freely through the hole 58 but has only limited rotation in this hole. The coupling 54, when the sucker rod is in its lowermost position, is spaced slightly above the upper face of the coupling 55 as shown in Fig. 5 and as a result should any accident happen during assembly the sucker rod and pistons can only drop into the working barrel until coupling 54 engages the stop member 56.

In Figs. 7 and 8 I show a modification of my invention wherein the parts are similar to those previously described, with like parts designated by single primed reference numerals. The difference in this modification resides in the fact that the valve member 59A consists ofA a cylindrical body 60A which is provided with spaced circumferential slots 6| and longitudinally cut grooves 62 which extend from each end of the body to the slots 6I. Intermediate the grooves GI the body includes a solid cylindrical portion 63. f

To complete the valve member a collar 64 is slid along the valve member until it engages the portion 63. lThis collar may be shrunk in place. Thereafter a pair of collars 65 are secured over the grooved portions 62. The collars 65 terminate at the inner ends of the groove 62 and may be held in place by shrinking them onto the end portions of the valve member. The assembly and operation of the device shown in Figs. '7 and 8 is similar in all other respects to that previously described.

In Fig. 9 I show a further modification. In this ligure parts like those previously described are designated by double primed reference numerals. In this further modification the valve member includes end collars 19 and an intermediate collar 1|. These collars receivefpacking l2 therebetween and the collars 'I0 are threaded at their ends. The sucker rod 23" passes through apertures in the intermediate and in the end collars. A sleeve 'I3 threadedly engages the end collars and is secured as by a drop of welding metal (not shown) to the intermediate collar.

The sleeve at each end thereof is threaded and receives at each end a ring 14. 'I'he rings 'I4 have spaced apertures 15 which extend therethrough and afford communication from the ends of the valve member to the portion of the valve member about the sleeve 13. The rings 14 receive a tube 1B which threadedly engages the rings. The tube 'I6 is provided with peripheral slots 11 similar to the slots 40 and 60 previously described and these slots are provided with apertures 18 which afford communication between the chamber about the sleeve and the tubular 'members 30" and 3|".

The tube 16 has a threaded portion 19 which receives a partition member 8U to thus prevent communication with the intermediate portion of the valve member. The arrangement in operation of the pump disclosed in Fig. 9 is similar in all respects to that described previously in connection with the other types.

From the foregoing description it will be apparent that I have invented a. novel dual pump which can be economically manufactured and assembled andv which can be operated in an economical manner.

Having thus described my invention, I claim:

l. A pump adapted to be inserted into a well casing, said pump comprising a discharge pipe, a mainpump barrel mounted in said discharge pipe and spaced therefrom, an enlarged cylinder mounted on the lower end of said barrel, said cylinder having its outer wall spaced from said discharge pipe and having spaced means affording ,communication between the interior of the cylinder and the exterior of the discharge pipe, a depending pump barrel on the lower end of said enlarged cylinder, said cylinder having an upper set and a lower set of circumfercntially aligned apertures affording communication between the interior of the cylinder and the space between the cylinder and the discharge pipe, said spaced means being arranged intermediate said sets of apertures, a sucker rod in said main pump barrel and extending through said cylinder and into said depending pump barrel, pistons on said sucker rod above and below said cylinder, a valve member slidable relative to said sucker rod and slidable within said cylinder, said valve member having outwardly directed holes' therein spaced from each end thereof, said valve member having communication forming means extending from the holes to the ends of the valve member, the length of said valve member being greater than the distance between said two sets of apertures and the length of the valve member being less than the distance from one set of argertures to the end of the working length of the cylinder which is remote from said one set of apertures.

2. A pump comprising a discharge pipe having a lower pump barrel projecting from the lower end thereof, a cylinder in said discharge pipe and above and communicating with said pump barrel, said cylinder including an outer wall portion spaced from said discharge pipe and an upper pump barrel above and communicating with the cylinder, upper tubular members ailording communication between the interiorof the cylinder and the exterior of the discharge pipe, lower tubular members affording communication between the interior of the cylinder and the exterior of the discharge pipe, said cylinder having upper and lower apertures affording communication between the interior of the cylinder and the space between the cylinder and the discharge pipe, said upper and lower tubular members being arranged intermediate said sets of apertures, a sucker rod in said pump barrels and said cylinder, pistons on said sucker rod in said pump barrels, a valve member slidable relative to said sucker rod and slidable Within said cylinder, said valve member' including a wall portion having upper and lower outwardly directed holes, the upper holes being out of communication with the lower holes, said valve member having channels extending inwardly from each end thereof and communicating with the associated holes, the length of said valve member being greater than the distance between said upper and lower apertures and the length of the valve member being less than the distance from the upper apertures to the lower end of the working length of the cylinder.

3. In a pump, a working barrel, a sucker rod in said barrel, spaced pistons on the sucker rod and in the barrel, said barrel including a cylinder between the pistons, a discharge pipe secured to the working barrel and spaced from said cylinder, axially spaced conduit means affording communication between the interior of the cylinder and the exterior of the discharge pipel other axially spaced conduit means affording communication between the interior of the cylinder and the space between the cylinder and the discharge pipe, said rst conduit means being between said other spaced conduit means, valve means slidable in' the cylinder and relative to the sucker rod and movable to two extreme positions, said valve including passages leading inwardly from each end thereof and directed to the outer surface of the valve means, said valve means in one position serving to simultaneously place the lower cylinder in communication with the exterior of the discharge pipe and the upper cylinder in communication with the space between the pump barrel and the discharge pipe, said valve means in the other position serving to simultaneously place the lower cylinder in communication with the space between the pump barrel and the discharge pipe and the upper cylinder in communication with the exterior of the discharge pipe.

4. In a pump, a working barrel, a sucker rod in said barrel, spaced pistons on the sucker rod and in the barrel, said barrel including a cylinder between the pistons, a discharge pipe spaced from said cylinder, spaced conduit means affording communication between the interior of the cylinder and the exterior of the discharge pipe, other spaced conduit means affording communication between the interior of the cylinder and the space between the cylinder and the discharge pipe, Said i-lrst mentioned conduit means being between said other spaced conduit means, valve means slidable in the cylinder and slidable relative to the sucker rod and movable to two extreme positions, said valve means including passages leading inwardly from each end thereof and directed to the outer surface of the valve means, said valve means in one extreme position serving to simultaneously'place the lower cylinder in communication with the exterior of the discharge pipe and the upper cylinder in communication with the space between the pump barrel and the discharge pipe, said valve means in the other extreme position serving to simultaneously place the lower cylinder in communication with the space between the pump barrel and the discharge pipe and the upper cylinder in communication with the exterior of the discharge pipe.

5. A lpump adapted to be inserted into a well casing, said pump comprising a discharge pipe, va

working barrel mounted in said discharge pipe cluding a cylinder spaced from said discharge pipe and having spaced means aiording communication between the interior of the cylinder and the exterior of the discharge pipe, said cylinder having an upper set and a lower aperture aording communication between the interior of the cylinder and the space between the cylinder and the discharge pipe, said spaced means being arranged intermediate said apertures, a sucker rod in said working barrel, pistons on said sucker rod above and below said cylinder, a valve member slidable relative to said sucker rod and slidable within said cylinder, said valve member having outwardly directed holes therein spaced from each end thereof, said valve member having communication forming means extending from the holes to the ends of the valve member, the length of said valve member being greater than the distance between said two sets of apertures and the length of the valve member being less than the distance from one set of apertures to the end of the working length of the cylinder which is remote from said one set of apertures.

f 6. A pump comprising a discharge pipe having a lower pump barrel projecting from the lower end thereof, a cylinder in said discharge pipe and above and communicating with said pump barrel, said cylinder including an outer wall portion spaced from said discharge pipe, an upper pump barrel above and communicating with the cylinder, upper means and lower means affording communication between the interior of the cylinder and the exterior of the discharge pipe, said cylinder having upper means and lower means aording communication between the interior of the cylinder and the space between the cylinder and the discharge pipe, said first mertionedl upper and lower means being arranged intermediate said second mentioned upper and lower means, a sucker rod in said pump barrels and said cylinder, pistons on said sucker rod in said pump barrels, a valve member slidable relative to said sucker rod and slidable within said cylinder, said valve member including a wall portion having upper and lower outwardly directed holes, the upper holes being out of communication with the' lower holes, said upper holes being aligned with I between said second mentioned upper and lower means and the length of the valve member being less than the distance from the rst mentioned upper means tothe lower end of the working length of the cylinder.

7. A pump adapted to be inserted into a well casing, said pump comprising a discharge pipe, a main pump barrel in said discharge pipe and spaced therefrom, a cylinder on the lower end of said barrel, said cylinder including an outer wall portion spaced from said discharge pipe, upper tubular members affording communication between the interior of the cylinder and the exterior of the Vdischarge pipe, lower` tubular members affording communication between the interior of the cylinder and the exterior of the discharge pipe, said upper and lower members beingV axially spaced apart, a depending pump barrel on the lower end of said cylinder, said cylinder hav? ing upper and lower apertures affording communication between the interior of the cylinder c and the space between the cylinder and the dis` charge pipe, said upper and lower tubular members being arranged intermediate said sets of apertures, a sucker rod in said pump barrels andv said' cylinder,`pistons on said sucker rod in said f pump barrels, a valve member slidable relative to said sucker rod and slidable within said cylinder, said valve member including a wall portion having upper and lower outwardlydirected holes, the upper holes being out of communication with the lower holes, said valve member having channels extending inwardly from each end thereof and communicating with the associated holes, the 3 length of said valve member being greater than the distance between said upper and lower apertures and the length of the valve member being less than the distance from the upper apertures to the lower end of the working length of the cylinder.

8. A pump comprising a discharge pipe having a lower pump barrel projecting from the lower end thereof, al cylinder in said discharge pipe and above and communicating with said pump barrel, said cylinder including an outer wall portion spaced from said discharge pipe and an upper pump barrel above and communicating with the cylinder, upper means and lower means aording communication between the interior of the cylinder and the exterior of the discharge pipe, said cylinder having upper means and lower means affording communication between the interior of the cylinder and the space between the cylinder and the discharge pipe, said rst mentioned upper and lower meansbeing arranged intermediate said second mentioned upper and lower means, a sucker rod in said pump barrels and saidcylinder, pistons on said sucker rod in said pump barrels, a valve member within said cylinder, said valve member including a wall portion having outer circumferential slots and having upper and lower outwardly directed holes intersecting said slots, the upper holes beingl out of communication with the lower holes, said upper holes being aligned with the said rst upper means when the valve member is up and the lower holes being aligned with the said rst lower means when the valve member is down, said valve member having channels extending inwardly from each end thereof and communicating with said holes, said valve member being movable to one position to open the first mentioned upper means and to close the second mentionedupper means while simultaneously closing the rst mentioned upper 75 means and opening the second mentioned lower means, and to a second position to close the rst mentioned upper means and to open the second mentioned upper means while simultaneously 5y opening the first mentioned upper means and closing the second mentioned lower means.

9. A pump adapted to be inserted into a well casing, said pump comprising a discharge pipe, a main pump barrel mounted in said discharge pipe and spaced therefrom, an enlarged cylinder mounted on the lower end of said barrel, said cylinder having its outer wall spaced from said discharge pipe, a set comprising a plurality of circumferentially aligned, spaced,'tubular members affording communication between the interior of the cylinder and the exterior of the discharge pipe, a second set comprising a plurality of circumferentially aligned, spaced, tubular members affording communication between the interior of the cylinder and the exterior of the discharge pipe, said sets being r'axially spaced apart, a depending pump barrel on the lower end of said enlarged cylinder, said cylinder having an upper set and a lower set of circumferentially aligned apertures affording communication between the in- Iterior of the cylinder and the space between the cylinder and the discharge pipe, said sets of tubular members being arranged intermediate said sets of apertures, a sucker rod in said main pump barreland extending through said cylinder and into said depending pump barrel, pistons on said sucker rod above and below said cylinder, a valve member slidable relative to said sucker rod and slidable within said cylinder, said valve member 5 having channels extending inwardly from each end thereof and having outwardly directed holes communicating with the inner ends of the channels,

the length of said valve member being greater than the distance between said two sets of aper- 40 tures and the length of the valve member being less than the distance from one set of apertures to the end of the working length of the cylinder which is remote from said one set of apertures.

10. A pump adapted to be inserted into a well casing, said pump comprising a discharge pipe, a main pump barrel mounted in said discharge pipe and spaced therefrom, an enlarged cylinder threadedly mounted on the lower end of said barrel, said cylinder having its outer wall spaced from said discharge pipe, a set comprising a plurality of circumferentially aligned, spaced, tubular members 'affording communication between the interior of the cylinder and the exterior of the discharge pipe, a second set comprising a plurality of cireumferentially aligned, spaced, tubular members affording communication between the interior of the cylinder and the exterior of the discharge pipe, said sets being axially spaced apart, a depending pump barrel threadedly engaging the lower end of said enlarged cylinder, said cylinder having an upper set and a lower set of circumferentially aligned apertures affording communication between the interior of the cylinder and the space between the cylinder and the discharge pipe, said sets of tu bular members being arranged intermediate said sets of apertures, a sucker rod in said main pump barrel and extending through said cylinder and into said depending pump barrel, a piston on said sucker rod in said main pump barrel and above said cylinder, a second piston on said sucker rod in the depending pump barrel and below the cylinder, a valve member slidable relative to said sucker rod and slidable within said cylinder', said valve member including a wall portion having an upper and a lower set of outwardly directed and circumferentiallyaligned holes, the holes of one set being out of communication with the holes of the other set, said valve memberhaving chan-r nels extending inwardly from each end thereof and communicating with the respective sets of holes, the length of said valve member being greater than the distance between said two sets of apertures andthe length of the valve member being less than the distance from one set of apertures to the end of the working length of the cylinder which is remote from said one set of apertures.

11. For use in a pump, a discharge pipehaving a lower pump barrel projecting from ythe lower end thereof, a cylinder in-saiddischarge pipe and above and communicating withsaid pump barrel, said cylinder including -an outer wall portion spaced from said discharge pipe and an upper pump barrel above and communicating with the cylinder, upper tubular members affording communication between the'interior of the cylinder and the exterior ofthedischarge pipe, and lower tubular members affording communication between the interior of the cylinder vand the exterior of the discharge pipe,said cylinder having upper and lower apertures affording communication between the interior of the cylinder and the space between the cylinder and the discharge pipe, said upper and lower tubular members being arranged intermediate said sets of apertures.

12. A working barrel fora pump, comprising a main pump barrel, an enlarged cylinder mounted on the lower end of said barrel, a set/of circumferentially arranged, spaced, tubular members projecting outwardly from said cylinder, a second set of circumferentially arranged, spaced,tubular members projecting outwardly from said cylinder, said sets being axially spaced, a depending pump barrel on the lower end of said enlarged cylinder, said cylinder having an upper set and a lower set of circumferentially aligned apertures affording communication between the interior of the cylinder and the space between the cylinder and the discharge pipe, said sets of tubular members being arranged intermediate said sets of apertures, a sucker rod in said main pump barrel and extending through said cylinder and into said depending pump barrel, pistons on said sucker rod above and below said cylinder, ,a valve member slidable relative to said sucker rod and slidable within said cylinder, said valve member having channels extending inwardly from each end thereof and having outwardly directed holes communicating with the inner ends of the channels, the length of said valve member being greater than the distance between said two sets of apertures and the length of the valve member being less than the distance from one set of apertures to the end of the working length of the cylinder which is vremote from said one set of apertures.

13. A pump comprising a discharge pipe, a main pump barrel mounted in said discharge pipe and spaced therefrom, an enlarged cylinder on the lower end of said barrel, said cylinder having its outer wall spaced from said discharge pipe, a pair of sets of circumferentially aligned, spaced, tubular members affording communication between the interior of the cylinder and the exterior of the discharge pipe, said sets being axially spaced apart, a depending pump barrel on the lower end of said enlarged cylinder, said cylinder having an' upper set-and a lower set of circumferentially aligned apertures affording communication between the interior of the cylinder and the space between the cylinder and the discharge pipe, said sets of tubular members being arranged intermediate said sets of apertures, a sucker rod in said main pump barrel and extending vthrough said cylinder and intosaid dependingpump barrel, a piston on said sucker rod in' saidmain `pump barrel v.and abovesaid cylinder, a' second piston on said sucker rod in the depending pump barrel andA below the cylinder, a valve member slidable on said sucker rod and Within said cylinder, said valve member including end collars and an intermediate collar all slidable relative to said sucker rod, a sleeve threadedly engaging said end collars and secured to said intermediate collar, a ring threaded on said sleeve at the ends thereof, said rings having spacedv apertures therein, a tube threadedly engaging said rings, said tube having a pair of spaced circumferential recesses therein in the outer wall and having apertures extending through said wall at the bottom of said recesses, a partition member threadedly engaging the interior of said sleeve, said partition member being disposed between said recesses, the length of said valve member being greater than the distance between said two sets of apertures and the length of the valve member being less than the distance from one set of apertures to the end of the working length of the cylinder which is remote from said one set of apertures.

14. A pump adapted to be inserted into a well casing, said pump comprising a discharge pipe, a main pump barrel mounted in 4said discharge pipe and spaced therefrom, a cylinder mounted on the lower end of said barrel, there being a passage for iiuid between said cylinder and said discharge pipe, axially spaced means affording communication between the interior of the cylinder and the exterior of the discharge pipe, a

`depending pump barrel on the lower end of said cylinder,` said cylinder having axially spaced apertures aiording communication between the interior of the cylinder and the said fluid passage, said axially spaced means being arranged intermediate said apertures, a sucker rod in said main pump barrel and extending through said cylinder and into said depending pump barrel, pistons on said sucker rod in said main pump barrel and in said depending pump barrel, a valve member slidable relative 'to said sucker rod and slidable within said cylinder, said valve member having outwardly directed holes therein spaced from each end thereof, said valve member having communication forming means extending from the holes towards the ends of the valve member, said communication forming means having axially spaced outlets spaced from said holes, the distance between said outlets being greater than the distance between said axially spaced apertures and the distance between said outlets being less than the distance from one of said axially spaced apertures to the end of the working length of the cylinder which is remote from said one aperture.

I5. In a pump, a working barrel, a sucker rod in said'barrel, spaced pistons on the sucker rod and in the barrel, said barrel including a cylinder between the pistons, a discharge pipe about the working barrel, there being a longitudinal passage for fluid, said passage being located between the interior of said cylinder and the exterior of the discharge pipe, axially spaced means affording communication between thc interior of the cylinder and the exterior of the discharge pipe, other axially spaced means aiording communication between the interior 0f the cylinder and said passage` said first com munication affording means being between ysaid second spaced communication affording means, a

valve slidable in the cylinder and relative to the l,

sucker'rod and movable to two extreme positions, said valve including passages operative in one position of the valve to piace the lower portion of lthe cylinder in communication with the exterior of the discharge pipe and the upper portion of cation with the exterior ot the discharge pipe.

WALTER E. CUMMINS. 

